The flow drag ones where they use a big ball and a force gauge the presenter just says its curious or something like that. What its actually demonstrating is not explained but its this; Its demonstrating the transition from laminar to turbulent flow of the air stream. The part where the force gauge reads lower force before increasing again even though the air speed is increasing is demonstrating that the air jet is going through transitional flow. Once the jet air stream velocity starts transitional and then into turbulent flow more energy is needed from the air per unit of force upon the ball.